Method for enhancing amidohydrolase activity of fatty acid amide hydrolase

ABSTRACT

A method for enhancing amidohydrolase activity of Fatty Acid Amide Hydrolase (FAAH) is disclosed. The method comprising administering a phenoxyacyl-ethanolamide that causes the enhanced activity. The enhanced activity can have numerous effects on biological organisms including, for example, enhancing the growth of certain seedlings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and is a divisional of, U.S. patentapplication Ser. No. 14/761,826 (filed Jul. 17, 2015) which is anational stage entry of International Application PCT/US14/12074 (filedJan. 17, 2014) which claims priority to U.S. Patent Application Ser. No.61/754,252 (filed Jan. 18, 2013) and U.S. Patent Application Ser. No.61/898,935 (filed Nov. 1, 2013). The entirety of each of theaforementioned patent applications is hereby incorporated herein byreference.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with U.S. Federal Government support undercontract number EY022774 awarded by the NIH National Eye Institute;contract numbers AG022550 and AG027956 awarded by the NIH Institute onAging; contract number DE-FG02-05ER15647 awarded by the Department ofEnergy and Contract No. 1046099 awarded by NSF-CBET. The government hascertain rights in the invention.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to enhancers ofamidohydrolase activity. Fatty acid amide hydrolase (FAAH) belongs tothe superfamily of amidase signature proteins. FAAH enzymes are found indiverse groups of organisms including both plants and animals. FAAHenzymes hydrolyze a broad range of N-acylethanolamines (NAEs) tocorresponding free fatty acid and ethanolamine, and can also act onprimary acyl amides as well as acyl esters. In plants, one type of FAAHhas been characterized, whereas two distinct FAAHs have been describedin animal systems. The homology between plant (Arabidopsis) andmammalian (rat) FAAH proteins at the amino acid level is somewhat lowover the full length of the proteins. However, the amidase signaturesequence (with core catalytic residues) between plant and animal FAAHshare up to 60% similarity at the amino acid level. The X-raycrystallography data of the rat protein provided new insights about themode of action of this enzyme in NAE hydrolysis. Although no tertiarystructure has been determined yet for plant FAAH, a structural homologymodel was developed for the amidase domain of the Arabidopsis FAAHprotein and conserved catalytic residues were identified experimentally.

The activity of FAAH is a key regulatory feature of the NAE signalingpathway. The regulated accumulation of NAEs influences numerousfunctions in plants and animals. The functional activities andphysiological effects of NAEs are mostly terminated by their degradationto FFA and ethanolamine. In plants, NAEs are involved in seedlingestablishment and growth. Exogenously applied N-lauroylethanolamine (NAE12:0) arrests seedling growth and this is evident through marked changesin root architecture and elongation. This inhibitory effect of NAEs onseedling growth occurs in part through a complex interaction with ABA(abscisic acid) signaling machinery during the embryo-to-seedlingtransition that remains incompletely understood. On the other hand,reductions of endogenous seed NAE levels through the over-expression ofFAAH in Arabidopsis results in enhanced seedling growth and increasedsize of roots, cotyledons and other plant organs. Other physiologicalprocesses have been attributed to FAAH mediated alteration of NAE levelsin plants, such as flowering time which is induced by the expression andtranslocation of the FLOWERING LOCUS T (FT) protein from leaves to thevegetative meristem. FAAH over-expressing plants exhibited an earlyflowering phenotype in both inductive and non-inductive growthconditions, and this was associated with lower NAE levels and higherexpression of FT and other key flowering genes. Still other work hasattributed changes in host susceptibility to pathogens or changes inphytohormone signaling pathways with altered FAAH expression.

In animals, FAAH-mediated NAE changes are part of the so-called“endocannabinoid signaling pathway”, and this pathway plays a centralregulatory role in many physiological and behavioral processes. The mostwidely studied NAE in animal systems is the N-arachidonylethanolamine,known also as anandamide (NAE 20:4), but other NAE species withoverlapping or unique functions are known as well. As an exampleN-linoleoylethanolamine (NAE 18:2) or N-palmitoylethanolamine (NAE 16:0)are involved in neuron protection in the retinal ganglion cell layeragainst excessive extracellular glutamate and against oxidative stressfor the HT22 cells, respectively. Anandamide was identified as the firstendogenous ligand of the cannabinoid receptors (CB1 and CB2), and isinvolved in activating many of the important endocannabinoid pathways.Anandamide and other NAEs have been associated with different processessuch as pain modulation, memory, anxiety, appetite, etc. Their levelsare controlled largely through hydrolysis by FAAH. Thus, FAAH has becomea major therapeutic target for many disorders that involves NAEsignaling in situ.

Several approaches have been employed to increase the level of NAEs inplants or animals including the direct application of NAEs orpharmacological reagents that inhibit NAE degradation. Utilization ofgeneral and/or specific inhibitors of FAAH activity such asphenylmethylsulfonyl fluoride (PMSF),5Z,8Z,11Z,14Z-eicosatetraenyl-methyl ester phosphonofluoridic acid(MAFP) or 3′-(aminocarbonyl)[1,1′-biphenyl]-3-yl)-cyclohexylcarbamate(URB597) have been reported to elevate endogenous levels of NAE, and toextend or amplify processes regulated by NAE signaling. Geneticapproaches have been developed to reduce FAAH expression (FAAHknockouts) in mice and Arabidopsis, although this approach has shownlimited success, especially in plants where it appears that there areredundant pathways for NAE catabolism, and where it has been difficultto raise endogenous NAE levels dramatically in vivo. On the other hand,it has been possible to over-express FAAH in plants and reduce NAElevels to some extent to influence several physiological processesincluding growth, defense, and flowering. However, there is limitedinformation on chemical compounds that reduce the NAE content in plantand animal systems via enhanced FAAH activity.

Among the multitude of renewable resources, cashew nutshell liquid(CNSL) is an important by-product of the cashew nut industry that iscurrently used for green chemicals and technologies. More than 32% ofthe cashew shell is CNSL, the key constituent of CNSL being cardanol, abio based non isoprene lipid, comprising a rich mixture of phenoliclipids: 5% of 3-(pentadecyl)-phenol (3-PDP), 50% of3-(8Z-pentadecenyl)phenol, 16% of 3-(8Z,11Z-pentadecadienyl)phenol and29% of 3-(8Z,11Z,14-pentadecatrienyl)phenol. Cardanol's uniqueproperties stem from the varying degree of cis-double bonds and an oddnumber of hydrocarbons with easily accessible saturated and unsaturatedhydrocarbon chains.

The discussion above is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter.

BRIEF DESCRIPTION OF THE INVENTION

A method for enhancing amidohydrolase activity of Fatty Acid AmideHydrolase (FAAH) is disclosed. The method comprising administering aphenoxyacyl-ethanolamide that causes the enhanced activity. The enhancedactivity can have numerous effects on biological organisms including,for example, enhancing the growth of certain seedlings.

Disclosed in this specification is a method for enhancing amidohydrolaseactivity of fatty acid amide hydrolase. The method comprises steps ofadministering a phenoxyacyl-ethanolamide composition to a biologicalorganism such that hydrolysis of N-acylethanolamines (NAEs) by fattyacid amide hydrolase (FAAH) in the biological organism is enhancedrelative to a substantially identical biological organism that has notbeen administered with the phenoxyacyl-ethanolamide composition.

This brief description of the invention is intended only to provide abrief overview of subject matter disclosed herein according to one ormore illustrative embodiments, and does not serve as a guide tointerpreting the claims or to define or limit the scope of theinvention, which is defined only by the appended claims. This briefdescription is provided to introduce an illustrative selection ofconcepts in a simplified form that are further described below in thedetailed description. This brief description is not intended to identifykey features or essential features of the claimed subject matter, nor isit intended to be used as an aid in determining the scope of the claimedsubject matter. The claimed subject matter is not limited toimplementations that solve any or all disadvantages noted in thebackground.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features of the invention can beunderstood, a detailed description of the invention may be had byreference to certain embodiments, some of which are illustrated in theaccompanying drawings. It is to be noted, however, that the drawingsillustrate only certain embodiments of this invention and are thereforenot to be considered limiting of its scope, for the scope of theinvention encompasses other equally effective embodiments. The drawingsare not necessarily to scale, emphasis generally being placed uponillustrating the features of certain embodiments of the invention. Inthe drawings, like numerals are used to indicate like parts throughoutthe various views. Thus, for further understanding of the invention,reference can be made to the following detailed description, read inconnection with the drawings in which:

FIG. 1A depicts a chemical synthesis and structure of new NAE-likecompounds; compound 1: 3-N-pentadecylphenol (PDP); compound 2: cardanol;compound 3: PDP-methylester; compound 4: cardanol-methylester; compound5: 3-N-pentadecylphenolethanolamine (PDP-EA):[N-(2-hydroxyethyl)-2-(3-pentadecylphenoxy)acetamide]; compound 6:cardanolethanolamine (cardanol-EA) (mixture ofphenoxyacyl-ethanolamides); R, acyl chain;

FIGS. 1B and 1C are high-resolution mass spectrometry (HRMS) forphenoxyacyl-ethanolamides (a) 3-N-pentadecylphenolethanolamine([M+H]⁺=m/z 406.3321 and its ¹³C isotopic peak [M+H]⁺=m/z 407.3362); (b)cardanol-ethanolamide (with three unsaturation: [M+H]⁺=m/z 400.2845 andits ¹³C isotopic peak [M+H]⁺=m/z 401.2881; with two unsaturation:[M+H]⁺=m/z 402.2996 and its ¹³C isotopic peak [M+H]⁺=m/z 403.3030; withsingle unsaturation: ([M+H]⁺=m/z 404.3163 and its ¹³C isotopic peak[M+H]⁺=m/z 405.3199; saturated: ([M+H]⁺=m/z 406.3297 and its ¹³Cisotopic peak [M+H]⁺=m/z 407.3332);

FIG. 2A, FIG. 2B and FIG. 2C are SDS-PAGE and Western blots of theenriched At-FAAH1 or rat FAAH from E. coli on a 12.5% polyacrylamidegel; wherein FIG. 2A, is a SDS-PAGE and western blot of differentfractions of the plant FAAH protein purification; FIG. 2B is a SDS-PAGEand western blot of different fractions of the rat FAAH proteinpurification, wherein Lane 1, supernatant (lysis); lane 2, flow through;Lane 3, wash fraction; Lane 4 eluted fraction; MM, molecular marker(molecular weight are represented in kilodaltons); lane 5, western blotprobed with mouse monoclonal anti-HIS antibodies;

FIG. 2C shows a “Detergent effect” (Triton X-100) on the amidohydrolaseactivity (AHase) of the At-FAAH in presence of PDP-EA or cardanol-EA,wherein reactions were initiated by addition of 0.3 μg of purifiedprotein extracted with 1% Triton X-100 or with 0.2 mM of DDM in thepresence of 100 μM of PDP-EA (or cardanol-EA); reactions were carriedout in 50 mM Bis-Tris propane-HCl (pH 9.0), 0.2 mM DDM at 30° C. for 30minutes in a final volume of 0.15 ml; data points represent means±S.D.of triplicate assays; plots were generated with SigmaPlot softwareversion 12.0;

FIG. 3 illustrates a TLC analysis of the lipid composition of theamidohydrolase assay with At-FAAH or rat FAAH and different substrate;reactions were initiated by the addition of purified At-FAAH or rat FAAHprotein (2 μg) with 50 mM of Bis-Tris propane-HCl (pH 9.0), 0.2 mM DDMat 30° C. for 2 hours, 120 rpm and 200 μM different potential substratesin a final volume of 0.3 ml; lipids were extracted and then separated byTLC (hexane/diethyl ether/acid acetic, 80:20:2, v/v/v); positions of theorigin (intact acylethanolamides) and the free fatty acid (FFA) 12:0 areindicated (arrows);

FIGS. 4A to 4G illustrate representative radiochromatograms of the total[1-¹⁴C]-lipid lipid components of following FAAH reactions in presence(or absence) of 100 μM of PDP-EA or cardanol-EA; reactions wereinitiated by the addition of purified rat or At-FAAH protein (0.3 μg)with 50 mM of Bis-Tris propane-HCl (pH 9.0), 0.2 mM DDM and 100 μM[1-¹⁴C]-NAE 12:0 in a final volume of 0.15 ml; reactions proceeded at30° C. with shaking (120 rpm) for 25 min; wherein FIGS. 4A to 4C show areaction with At-FAAH protein, solvent control (DMSO); with 100 μM ofPDP-EA; with 100 μM of cardanol-EA; FIG. 4D to 4F show a reaction withrat FAAH protein, solvent control (DMSO); with 100 μM of PDP-EA; with100 μM of cardanol-EA; FIG. 4G shows assays with heat-denaturatedAt-FAAH protein (5 minutes at 100° C.) plus cardanol-EA (100 μM); lipidswere extracted and separated by TLC (60:40:5; v/v/v); chromatograms wereobtained by radiometric scanning of the TLC plate;

FIGS. 5A and 5B depict amidohydrolase activity (μmol/min/mg of protein)of purified At-FAAH or rat FAAH protein with different[1-¹⁴C]N-acylethanolamines (NAEs) in presence of 100 μM of PDP-EA orcardanol-EA; wherein FIG. 5A shows assays with purified At-FAAH (0.3μg); FIG. 5B shows assays with purified rat FAAH (0.3 μg); reactionswere carried out in 50 mM Bis-Tris propane-HCl (pH 9.0), 0.2 mM DDM at30° C., 30 minutes, with shaking (120 rpm) in a final volume of 0.15 ml;data points represent means±S.D. of triplicate assays; plots weregenerated with SigmaPlot software version 12.0. P-value of <0.05, <0.01,is indicated by * and **, respectively, as determined by student's ttest. ns, not significant.

FIGS. 6A, 6B and 6C depict a kinetic characterization of At-FAAH1p andrat FAAH in presence of 100 μM PDP-EA or cardanol-EA; initial velocitieswere measured at increasing concentrations of [1-¹⁴C]-NAE 12:0 forAt-FAAH (FIG. 6A); or [1-¹⁴C]-NAE 20:4 for rat FAAH (FIG. 6B). Reactionswere initiated by the addition of purified protein (0.3 μg). (FIG. 6C),represent the apparent kinetic parameters of the enzymes estimated bytransformations of these original data (i.e., double-reciprocal plots).Reactions were carried out in 50 mM Bis-Tris propane-HCl (pH 9.0), 0.2mM DDM at 30° C. in a final volume of 0.15 ml. Data points representmeans±S.D. of triplicate assays. Velocity in μmol/min/mg of protein.Plots were generated with Prism software version 3.0 (GraphPad Software,San Diego), and data were fitted to a nonlinear regression (curve fit)using one site binding (hyperbola) equation with a R² between 0.89 to0.98 for the At-FAAH curves and between 0.93 to 0.98 for the rat curves;

FIGS. 7A and 7B show inhibition of At-FAAH1 or rat FAAH proteins atincreasing concentrations of ethanolamine (EA) and protection frominhibition by 100 μM of PDP-EA or cardanol-EA. Reactions were initiatedby the addition of 0.3 μg of At-FAAH (FIG. 7A) or with rat FAAH (FIG.7B) purified proteins. Reactions were carried out in 50 mM Bis-Trispropane-HCl (pH 9.0), 0.2 mM DDM at 30° C. with 100 μM of [1-¹⁴C]-NAE12:0 in a final volume of 0.15 ml. Data points represent means±S.D. oftriplicate assays. Plots were generated with SigmaPlot software version12.0;

FIG. 8 illustrates a characterization of NAE sensitivity and NAEamidohydrolase activity for Arabidopsis seedlings in the presence orabsence of PDP-EA or cardanol-EA; panel A, Arabidopsis thaliana wildtype (Col-0) seedlings with 30 μM NAE 12:0; panel B, Seedlings plus 30μM NAE 12:0 and 20 μM cardanol-EA; panel C, Seedlings plus 30 μM NAE12:0 and 20 μM PDP-EA, panel D, images of the cotyledon sizes ofseedlings in presence of 20 μM of phenoxyacyl-ethanolamide compounds+/−30 μM of NAE 12:0; seedlings were grown with these differenttreatments for 11 days under long day conditions. panel E and panel F,show the sizes of the cotyledons or roots as a function of differentNAE, PDP-EA or cardanol-EA concentrations. panel G, FAAH activity,reactions were initiated by the addition of 6 μg of crude plant proteinextract from 11-d-old seedlings in 50 mM Bis-Tris propane-HCl (pH 9.0),0.2 mM DDM at 30° C. for 2 hours with 200 μM of [1-¹⁴C]-NAE 12:0 and 200μM of NAE-like compounds in a final volume of 0.3 ml; data pointsrepresent means±S.D. of triplicate assays; plots were generated withSigmaPlot software version 12.0. N+C-EA (NAE 12:0+cardanol-EA); meanswith different letters are significantly different (P<0.005) determinedby one-way ANOVA with Tukey's post-test; and

FIGS. 9A, 9B, 9C and 9D are cardanol-EA pre-treatment sensitizes primarycortical neurons to oxidative insult in a FAAH-dependent manner; rat E18cortical neurons were pre-treated for 1-2 hours with cardanol-EA priorto an overnight (16-18 hour) tBHP exposure; the cardanol-EA stocksolution was pre-diluted 1:5 in 2-hydroxypropyl-β-cyclodextrin prior todilution in media to enhance delivery; neuronal viability was measuredby calcein fluorescence and normalized to the vehicle control; FIG. 9A,Cardanol-EA pre-treatment exacerbates tBHP-mediated cell death; FIG. 9B,the bioactive lipid NAE 16:0, a substrate of FAAH, reverses this effect;FIG. 9C, FIG. 9D, Cardanol-EA treatment significantly reduces neuronalviability in anti-oxidant free media and exacerbates tBHP-mediated celldeath; pre-incubation with the specific, irreversible, FAAH inhibitorsMAFP and URB597 block this effect of cardanol-EA; data points representmeans±SEM of triplicate assays; plots were generated with GraphPad Prismversion 5.0; A P-value of <0.05, <0.01, and <0.001 is indicated by *,**, and ***, respectively, as determined by one-way ANOVA with Dunnett'spost-test.

DETAILED DESCRIPTION OF THE INVENTION

N-Acylethanolamines (NAEs) are involved in numerous biologicalactivities in plant and animal systems. The metabolism of these lipidsby fatty acid amide hydrolase (FAAH) is a key regulatory point in NAEsignaling activity. Several active-site-directed inhibitors of FAAH havebeen identified, but few compounds have been described that enhance FAAHactivity. Disclosed in this specification are phenoxyacyl-ethanolamidessynthesized from natural products, 3-N-pentadecylethanolamine (PDP-EA)and cardanolethanolamide (cardanol-EA), with structural similarity toNAEs. Their effects on the hydrolytic activity of FAAH werecharacterized. Both compounds increased the apparent V_(max) ofrecombinant FAAH proteins from both plant (Arabidopsis) and mammalian(Rattus) sources. These NAE-like compounds appeared to act by reducingthe negative feedback regulation of FAAH activity by free ethanolamine.Both compounds added to seedlings relieved, in part, the negative growtheffects of exogenous NAE12:0. Cardanol-EA reduced neuronal viability andexacerbated oxidative stress-mediated cell death in primary culturedneurons at nanomolar concentrations. This was reversed by FAAHinhibitors or exogenous NAE substrate. Collectively, our data suggestthat these phenoxyacyl-ethanolamides act to enhance the activity of FAAHand may stimulate the turnover of NAEs in vivo. Hence, these compoundsmight be useful pharmacological tools for manipulating FAAH-mediatedregulation of NAE signaling in plants or animals.

Here, we synthesized a new set of phenoxyacyl-ethanolamides from thisrenewable resource with structural similarity to NAEs and investigatedtheir effects on the FAAH activity. These phenoxyacyl-ethanolamides werenot substrates for FAAH; however, we measured a positive effect of thesecompounds on NAE hydrolysis by recombinant FAAH. The increase in enzymeturnover rate likely is through relief from product inhibition byethanolamine, a property not previously appreciated for either plant ormammalian FAAH enzymes. It is possible that compounds like thesephenoxyacyl-ethanolamides, might prove useful in manipulating NAE levelsin vivo through their actions on FAAH.

Phenoxyacyl-Ethanolamide Synthesis—

We developed a simple method that proceeds by refluxing the mixture ofphenolic lipids 3-PDP (compound 1 in FIG. 1A, where R is n-pentadecyl))or cardanol (compound 2 in FIG. 1A, where R is C₁₅H₁₉ (50%); C₁₅H₂₅(29%); C₁₅H₂₇ (16%); C₁₅H₃₁ (5%) and methylbromoacetate in the presenceof K₂CO₃ as a base and 2-butanone as a solvent to generate the desiredPDP-methylester 4 or cardanol-methylester 5. Amide bond formation ofmethylester by chemoselective reaction with ethanolamine asN-nucleophile in dry dichloromethane and triethylamine as base yieldedthe desired phenoxyacyl ethanolamides 5,6 in good yield and purity(supplemental data FIG. 1B and FIG. 1C). The products were separated bycolumn chromatography and characterized by both NMR spectroscopy (¹H and¹³C NMR) and mass spectrometric analysis. ¹H NMR spectra of compound 5and 6 (FIG. 1A) showed signals at δ 7.1 ppm for —NH proton and δ 2.7 ppmfor —OH proton respectively. The exchangeable nature of these protonswas identified using D₂O exchange studies. High resolution mass spectralanalysis of PDP-EA and cardanol-EA showed a molecular ion peak (M+H⁺) atm/z 406.3321 and m/z 404.3163 respectively, which exactly matches withthe theoretically calculated value (PDP-EA: [M+H]⁺, m/z 406.3321 &cardanol-EA: [M+H]⁺, m/z 404.3165). These new NAE-like compounds, namedas 3-N-pentadecylphenolethanolamine (PDP-EA, 406.3 g·mol⁻¹) andcardanol-ethanolamide (cardanol-EA 404.3 g·mol⁻¹), were dissolved as 10mM stock solutions in DMSO for assays.

Protein Purification and Amidohydrolase Assays—

Enzymatic assays were performed with two different purified recombinantproteins: Arabidopsis thaliana FAAH (AT-FAAH) (UniProt #Q7XJJ7) and ratFAAH (NCB accession #NP_077046). Expression and purification of theseproteins were monitored by SDS PAGE and Western blotting (FIG. 2A andFIG. 2B). Bands observed in the SDS-PAGE gel are consistent with themolecular weights calculated for each protein plus the HIS tag(C-terminus of the protein), which are 70 kDa for At-FAAH and 66 kDa forrat FAAH. Both proteins were also detected by Western-blot using ananti-HIS tag monoclonal antibody with some unavoidable proteolyticdegradation evident (FIG. 2A and FIG. 2B, lane 5). The inclusion ofserine protease inhibitors was avoided so as not to influence FAAHactivity.

Utilization of Triton X-100 during protein extraction is mandatory torecover the activity of the rat protein, but not for At-FAAH(supplemental data FIG. 2C). However, AHase assays performed withAt-FAAH extracted in presence of 1% (v/v) Triton X-100 showed anincrease by a factor of about 10 for hydrolysis of NAE to FFA comparedto assays performed in 0.2 mM of DDM (supplemental data FIG. 2C). Thisincrease of activity could be explained by improved solubilization ofthe protein, the lipophilic NAE substrate, and/or FFA product. Forconsistency and optimal activity, extraction of recombinant proteins inTriton X-100 was performed for all subsequent experiments.

Enhanced NAE Amidohydrolase Activity with the Plant or Rat FAAH inPresence of PDP-EA and Cardanol-EA—

Neither of the NAE-like compounds (PDP-EA and cardanol-EA) appeared tobe hydrolyzed to their respective acid forms (PDP-acid andcardanol-acid) and ethanolamine by either the plant or animal FAAHenzymes (2 μg protein and 100 μM-300 μM substrate) (FIG. 3). Somewhatsurprisingly, compared to NAE 12:0, the phenoxyacyl-ethanolamides werenot suitable substrates for FAAH as might be anticipated from thepromiscuous nature of the FAAH enzymes.

To test whether these phenoxyacyl-ethanolamide might serve as inhibitorsof NAE hydrolysis by the FAAH enzymes, we measured the hydrolysis of 100μM of [1-¹⁴C]-NAE 12:0 with or without 100 μM of PDP-EA or cardanol-EA.Instead of reductions in FAAH activity as expected, the amidohydrolaseactivity of both FAAH enzymes toward NAE was increased in presence ofeither phenoxyacyl-ethanolamide compound (FIGS. 4A to 4G). Non-enzymatichydrolysis of NAE to free fatty acid by PDP-EA or cardanol-EA could beruled out since no activity was measured in assays usingheat-denaturated enzyme (FIG. 4G). FAAH activities toward differentNAEs, such as [1-¹⁴C]N-palmitoylethanolamine (NAE 16:0) or[1-¹⁴C]N-arachidonoylethanolamine (NAE 20:4, anandamide) showed asimilar enhancement in the presence of the new NAE-like compounds (FIG.5A and FIG. 5B). An increase of activity by a factor of about 4±1.2 forthe recombinant At-FAAH protein was measured in presence of eitherPDP-EA or cardanol-EA and by a factor of about 5±2.2 for the rat FAAHprotein for the unsaturated NAE (NAE 16:0 and NAE 12:0), and up to afactor 7±1.1 for the rat FAAH protein and NAE 20:4 (FIG. 5A and FIG.5B).

Kinetic Parameters of At- and Rat FAAH Proteins—

Each enzyme exhibited typical Michaelis-Menten-type kinetics wheninitial velocity measurements were made at increasing concentrations ofNAE 12:0 or NAE 20:4 substrates for At-FAAH or rat FAAH, respectively.Both apparent V_(max) (V_(max) ^(app)) and apparent K_(m) (K_(m) ^(app))were calculated for each enzyme and summarized (FIG. 6A, FIG. 6B, FIG.6C). No statistical difference (T-test, confidence level 95%) for theK_(m) ^(app) values of the At-FAAH was observed with or without 100 μMof either PDP-EA or cardanol-EA (FIG. 6A, FIG. 6B, FIG. 6C). However,catalytic efficiency (K_(cat)/K_(m)) of the At-FAAH enzyme increased inpresence of both phenoxyacyl-ethanolamides (9.8×10⁴M⁻¹/s⁻¹ or1.58×10⁵M⁻¹/s⁻¹ compared with solvent control of 3.8×10⁴M⁻¹/s⁻¹). TheK_(m) ^(app) obtained in our assays for the plant FAAH was similar toK_(m) values determined elsewhere (17.6 μM).

For the rat FAAH, there was an increase by a factor of about 3 of therat K_(m) estimated in presence of both phenoxyacyl-ethanolamidescompounds (173±18-179±25 μM) compared to that measured in solventcontrols (56±7.07 μM). Similar to At-FAAH, rat FAAH exhibited anincrease in K_(cat) in the presence of PDP-EA and cardanol-EA,indicating an increase in turnover rate of the recombinant protein withrespect to NAE. However, similar values of the ratio K_(cat)/K_(m) werecalculated for the rat FAAH with or without thephenoxyacyl-ethanolamides (due to reduced affinity of the enzyme for theNAE substrate), suggesting a similar catalytic efficiency of the ratenzyme with or without these compounds. Although there is variation inreported kinetic parameters for rat FAAH, those measured here weresimilar to those reported elsewhere.

Protection by Phenoxyacyl-Ethanolamides from Ethanolamine ProductInhibition for Both At- and Rat FAAH—

We noted a statistical dose-dependent reduction in NAE hydrolaseactivity at increasing ethanolamine concentrations (FIG. 7A and FIG.7B). While enzyme regulation by product inhibition is not uncommon,feedback inhibition of FAAH by ethanolamine has not been describedneither for rat nor for At-FAAH. We demonstrated that this regulatoryfeature is evident for both At-FAAH and rat FAAH. Perhaps even moreinteresting, both PDP-EA and cardanol-EA relieved this ethanolamineinhibition almost completely at concentrations up to 10 mM ethanolamine(FIG. 7A and FIG. 7B). No dramatic change in pH of the reaction wasmeasured following the addition of ethanolamine (−up to 10 mM, pH 9.0;at 100 mM, pH 9.7; 25° C.), indicating the inhibitory effects ofethanolamine were not due to alterations in reaction pH.

Effects of PDP-EA and Cardanol-EA on Plant Growth—

Negative effects on seedling growth by exogenous NAE 12:0 are welldocumented. PDP-EA and cardanol-EA were able to reverse partially thesenegative growth effects (FIG. 8). Representative images of Arabidopsisseedlings germinated and grown in media containing NAE 12:0 alone, orNAE 12:0 with PDP-EA or cardanol-EA, are shown in FIG. 8 (panels A-C).Quantitative measurements of seedling growth (cotyledon size and primaryroot elongation) are summarized in FIG. 8, panels E and F. Despite asomewhat similar structure to NAE 12:0, PDP-EA alone, and especiallycardanol-EA alone, showed a positive impact on seedling growth(cotyledon size, FIG. 8, panels D, E) opposite to the effects of NAE12:0. And both compounds partially reversed the negative effects of NAE12:0 with respect to cotyledon size. Cardanol-EA reversed negativegrowth effects of NAE 12:0 in primary roots. One potential explanationfor these effects on seedling growth by PDP-EA and cardanol-EA isthrough their biochemical enhancement of At-FAAH activity in vivo. FAAHoverexpression in transgenic Arabidopsis (with increased FAAH activity)conferred enhanced seedling growth as well as tolerance of the negativegrowth effects of NAE, with effects on cotyledon size and primary rootlength very similar to those observed here by adding thesephenoxyacyl-ethanolamides to non-transgenic seedlings (FIG. 8). Asexpected, NAE amidohydrolase activity from crude seedling extractsshowed an enhancement when assayed in the presence of PDP-EA orcardanol-EA and [1-¹⁴C]-NAE 12:0 (FIG. 8, panel G). Therefore, it ispossible that exogenous application of these phenoxyacyl-ethanolamidescan stimulate FAAH activity in planta and positively influences plantgrowth.

Effects of Cardanol-EA on Viability of Cultured Primary Neurons—

Treatment of cultured embryonic primary neurons with cardanol-EAexacerbated tert-butyl hydroperoxide-mediated (tBHP) cell death (FIG.9A-D). Following overnight exposure to oxidative stress induced bytreatment with 7.5 μM tBHP, neuronal cultures pre-treated with 1 μMcardanol-EA contained 18% fewer viable cells than cultures pre-treatedwith vehicle alone (FIG. 9A). Incubation of neurons with the exogenouslyadministered FAAH substrate, NAE 16:0 (N-palmitoylethanolamine) for 1hour prior to addition of 1 nM cardanol-EA resulted in a dose-dependentreversal of cardanol-induced exacerbation of tBHP mediated cell death(FIG. 9B). Primary neurons treated with cardanol-EA and incubated inanti-oxidant free media overnight demonstrated a significant reductionin viability compared to neurons incubated overnight in anti-oxidantfree media with vehicle or with the specific, irreversible, FAAHinhibitors MAFP and URB597 (FIG. 9C and FIG. 9D, respectively).Incubation of neurons with these inhibitors for one hour prior to theaddition of cardanol-EA completely reversed cardanol-inducedexacerbation of tBHP mediated cell death, suggesting that this ex vivoeffect of cardanol-EA is a result of FAAH activation.

Despite the structural similarity between the phenoxyacyl-ethanolamidecompounds synthesized for these studies (FIG. 1A) and the naturallyoccurring NAE lipids that are present in essentially all multicellulareukaryotes, neither of the FAAH proteins (rat or Arabidopsis) were able,in our conditions, to utilize these compounds efficiently as substratesfor hydrolysis (FIG. 3). This was somewhat surprising given the broadrange of acyl amides and acyl esters that can be hydrolyzed by FAAH. Onthe other hand, previous studies demonstrated that substitutions at theα-position of the acyl chain of primary amide or anandamide analoguescompounds rendered the compound resistant to hydrolysis by FAAH. Theincorporation of a bulky phenoxy-group near the amide moiety may serve asimilar structural hindrance to the enzyme's active site and restricthydrolysis. However, even if these newly synthesized lipids were notused as substrates by FAAH, we speculated that these compounds would actas inhibitors toward NAE hydrolysis. Instead, a rather uniquecharacteristic was identified for these compounds; we found that thesephenoxyacyl-ethanolamides functioned to stimulate hydrolysis of NAEs byFAAH (FIGS. 4A to 4G, FIGS. 5A and 5B, FIGS. 6A, 6B, and 6C). Thesecompounds stimulated the activity of FAAH from both plant and mammaliansources, suggesting a more general feature of FAAH, not specific to thetype of organism. There were subtle differences between plant andmammalian FAAH, such as the impact of the phenoxyacyl-ethanolamides onthe affinity of the enzyme toward NAEs (raised the K_(m) for NAE 20:4 inrat FAAH substantially, but did not statistically (T-test, confidencelevel 95%) affect the K_(m) for At-FAAH). On the other hand, in bothplant and mammalian FAAH, the turnover number of the enzyme wasincreased by addition of the phenoxyacyl-ethanolamides (FIGS. 6A to 6C).Moreover, a new negative feedback property of FAAH activity byethanolamine was discovered for both FAAH proteins and this wasprevented to a substantial degree by the addition of thephenoxyacyl-ethanolamides (FIGS. 7A and 7B).

The detergent Triton X-100 has been used extensively for thesolubilization and to enhance the recoverable activity of recombinantrat FAAH. This non-ionic detergent likely mimics somewhat the endogenousmembrane environment of FAAH and maintains the functional amidase andesterase activities of the enzyme toward lipophilic substrates. In thecase of At-FAAH, Triton X-100 appeared to be better than thealkylglycoside detergent, DDM, (FIG. 2C) historically used forsolubilizing active At-FAAH enzyme. However, K_(m) values measured herewere generally similar for At-FAAH solubilized in DDM (26±5.09 μM FIG.6C vs. 13-50 μM in previous studies), and this procedural change allowedfor more consistent comparisons between plant and animal FAAH enzymesfor our comparative studies. Even so, both PDP-EA and cardanol-EAenhanced FAAH activities from both plant and animal sources (FIGS. 4,5A, 5B, 6A, 6B and 6C), and prevented product inhibition by ethanolamineat least up to 10 mM (FIGS. 7A and 7B). The increase in FAAH turnovernumber measured in FIGS. 6A to 6C in the presence ofphenoxyacyl-ethanolamides may be a direct result of prevention ofproduct inhibition by ethanolamine, even in the case of rat FAAH wherethe affinity for NAE substrate appeared to be reduced by thephenoxyacyl-ethanolamide analogues. It still remains to be clarifieddirectly whether the effect of the phenoxyacyl-ethanolamides is via aspecific binding site on FAAH or is more general in terms of influencingFAAH or substrate solubility. However, the effects of these compounds onNAE-mediated inhibition of seedling growth or in the modulation ofneuronal cell death would suggest that these compounds indeed actthrough a specific effect on the FAAH enzyme per se.

NAE 12:0 inhibits seedling growth when applied exogenously (see FIG. 8,and also references). Co-application of PDP-EA and especiallycardanol-EA reversed these inhibitory growth effects of NAE 12:0 (FIG.8). Similarly, the overexpression of FAAH in transgenic Arabidopsisseedlings also results in an NAE tolerant phenotype. It is possible thatthe new phenoxyacyl-ethanolamides are able to enhance endogenous FAAHactivity in wild-type seedlings, to confer some tolerance to the growthinhibition by NAE 12:0. Certainly there are other possible mechanisms bywhich these phenoxyacyl-ethanolamides might be acting, and this areawill require further experimentation, but to date, only increasedactivity of FAAH has been shown to confer tolerance toward NAE 12:0, andthis is consistent with the in vitro action of PDP-EA and cardanol-EA onpurified recombinant FAAH enzymes (FIGS. 4-7B), and in crude seedlinghomogenates (FIG. 8, panel G).

One intriguing aspect of these compounds is their growth promotingproperties in seedlings (FIG. 8). This is especially evident forcardanol-EA and its influence on cotyledon size (FIG. 8, panels D andF). This is exactly the opposite effect of NAEs which appear to retardgrowth and reduce cotyledon size. Besides their antagonistic effects onNAE treatment in seedlings, it seems that these compounds have their owninherent growth regulating properties. Interestingly, seedlingsoverexpressing FAAH showed significant increases in cotyledon size (andother organs as well), again suggesting that thesephenoxyacyl-ethanolamides may be acting through modulation of endogenousFAAH activity.

The cardanol-EA-mediated reduction of cellular viability andexacerbation of oxidative stress induced cell death in primary neurons(FIGS. 9A, 9B, 9C and 9D) are potentially mediated by the depletion ofneuroprotective NAEs through an increase of FAAH activity (FIGS. 5A and5B). The reversal of cardanol's sensitizing effect on neuronal celldeath by NAE 16:0 begins well below its reported IC₅₀ of 5.1 μM foranandamide hydrolysis by rat brain FAAH, which may indicate thatcardanol-EA does not affect binding of NAE 16:0 to rat FAAH in the sameway that it does with anandamide (3.1 fold increase in K_(m); FIG. 6A to6C). The specificity of the pharmacological inhibitors of FAAH used toreverse cardanol-induced exacerbation of tBHP mediated cell death (FIG.9C and FIG. 9D), suggest FAAH activation as the underlying mechanism ofaction.

Cardanol-EA is a mixture of different phenoxyacyl-ethanolamides all withfifteen carbon alkyl chains (FIGS. 1A, 1B and 1C). Fifty percent of thismixture is composed of an alkyl chain with one double bond, 16% with twodouble bonds, 29% with three double bonds and with 5% of PDP-EA with nodouble bonds (saturated form). The PDP-EA compound is a single specieswith a fifteen carbon saturated alkyl chain. There may be some slightdifferences in terms of action on FAAH between the twophenoxyacyl-ethanolamide preparations, but generally, the stimulatoryactivity was observed for both compounds. The advantage of thecardanol-EA mixture is that it is synthesized from natural materialsfound in many plant sources. The starting materials for thesephenoxyacyl-ethanolamides are derived from cardanol, which are majorconstituents of cashew nut shell waste streams, and ethanolamidessynthesized from these phenolic lipids may find many applications beyondtheir chemical properties as lipophilic hydrocarbon polymers. Given theplant growth promoting properties, especially of cardanol-EA, there maybe agricultural applications for these compounds. Or based on theiraction on FAAH activity, these compounds may find therapeuticapplications where manipulation of localized endogenous NAE levels mightbe desired.

Overall, the activities of these two new NAE-like compounds (PDP-EA andcardanol-EA) open a new interesting and unexplored approach for the insitu regulation of NAE metabolism in plant and animal systems. Forexample these molecules might be used as pharmacological agents tomodulate appetite by decreasing the endogenous levels ofacylethanolamide agonists in animal systems, as chemo-sensitizing agentstargeted at lipid signaling pathways affected by disease processes or asa modulator of endocannabinoid signaling in applications ranging fromcytoprotection, to cellular development and excitable cell function. Inplants, NAE metabolism has been shown to be associated with biotic andabiotic stresses as well as seedling and reproductive growth anddevelopment. Hence, these compounds might find applications inagriculture. Further experiments will need to be done to define utilityof these FAAH enhancers in vivo to modulate the numerous effects of NAEsin plants and animals.

EXPERIMENTAL PROCEDURES

Materials—

[1-¹⁴C]-Lauric acid was from Amersham Biosciences, [1-¹⁴C]-palmitic acidwas purchased from NEN (Boston Mass.), and [1-¹⁴C]-arachidonic acid waspurchased from PerkinElmer Life Sciences. Ethanolamine, anandamide,isopropyl-β-D-thiogalactopyranoside (IPTG), Triton X-100 were from SigmaChemical Co (St. Louis). N-dodecyl-β-D-maltoside (DDM) was fromCalbiochem (LA Jolla, Calif.). Sprague/Dawley rat E18 cortical neurons,NeuroPapain, NeuroPrep medium, and NeuroPure plating medium wereobtained from Genlantis (San Diego, Calif.). Neurobasal media, B27supplement, B27 antioxidant-free supplement, GlutaMAX I, and calcein-AMwere purchased from Invitrogen. BD PureCoat™ amine plates were obtainedfrom BD Biosciences. DMSO and 2-hydroxypropyl-β-cyclodextrin werepurchased from Sigma Chemical Co. (St. Louis, Mo.). tert-butylhydroperoxide (tBHP) was obtained from Acros Organics (part of ThermoFisher Scientific, New Jersey). PBS and penicillin/streptomycin werepurchased from Lonza (Walkersville, Md.). Palmitoylethanolamide was fromBest West Laboratories (Salt Lake City, Utah), MAFP was from TocrisBiosciences, and URB597 was from EMD Millipore. Silica Gel G (60A)-coated glass plates for thin-layer chromatography (10 cm×20 cm or 20cm×20 cm, 0.25 mm thickness) were from Whatman (Clifton, N.J.).Different species of N-[1-¹⁴C]-acylethanolamines (and non-radiolabeledNAEs) were synthesized from ethanolamine and corresponding [1-¹⁴C]-fattyacids (and non-radiolabeled FFAs) by first producing the fatty acidchloride and purifying by thin layer chromatography (TLC) as describedelsewhere. The chemical compounds PDP-EA and cardanol-EA were producedas described below.

Synthesis of 3-N-Pentadecyl-Ethanolamide (PDP-EA) and the More GeneralMixed Species Cardanol-Ethanolamide (Cardanol-EA)—

For the cardanol-EA: In a round bottom flask fixed with magneticstirrer, cardanol-methyl ester (3.74 g, 10 mmol) was added, followed bydichloromethane (DCM) (25 mL) and Triethylamine (TEA) (1.4 mL, 10 mmol).Reaction mixture was stirred for 2 minutes, followed by the drop wiseaddition of ethanolamine (0.66 mL, 11 mmol) in an ice bath with constantstirring. The resultant mixture was stirred at room temperature forabout 6-8 h. After the completion of reaction, as identified using TLC,ice cold water was added and the lipids extracted with ethyl acetate.The organic phase was separated and dried over anhydrous sodium sulfate,filtered, and concentrated. Pure product as a colorless liquid wasobtained by column chromatographic purification. At 5° C., the viscousliquid solidifies in to pale yellow solid. Yield=78%. ¹H NMR (CDCl₃, 300MHz): δ 7.17 (s, 2H), 6.68-6.83 (m, 3H), 5.36 (d, 3H), 4.45 (s, 2H),3.72 (s, 2H), 3.49 (s, 3H), 2.78 (s, 1H), 2.56 (d, 2H), 2.14 (s, 1H),2.01 (s, 2H), 0.86-1.57 (m, 20H); ¹³C NMR (CDCl₃, 75 MHz): δ 169.91,157.33, 145.25, 130.28, 130.15, 130.00, 129.68, 122.58, 122.43, 115.18,114.99, 111.88, 111.69, 67.36, 61.85, 42.04, 36.15, 31.99, 31.59, 29.93,29.45, 29.41, 22.89, 14.33. High-resolution MS analysis showed [M+H]⁺,m/z 404.3163 (for the principal ethanolamide species in the cardanol-EApreparation) compared to the calculated mass for C₂₅H₄₁NO₃, [M+H]⁺ ofm/z 404.3165. To synthesize and purify the PDP-EA[N-(2-hydroxyethyl)-2-(3-entadecylphenoxy) acetamide], a similar schemewas used as for cardanol EA, except pure PDP methyl ester was used togenerate the acylethanolamide. Purity of crude product was greater than90%. Pure PDP-EA product, as colorless crystals, was obtained by columnchromatographic purification. Yield=92%. ¹H NMR (CDCl₃, 300 MHz): δ 7.18(s, 2H), 6.84 (s, 1H), 6.73 (s, 2H), 4.77 (s, 1H), 4.47 (s, 2H), 4.11(s, 1H), 3.72 (s, 2H), 3.45 (s, 2H), 2.56 (s, 2H), 2.02 (s, 1H), 1.57(s, 2H), 1.25 (s, 22H), 0.87 (s, 3H); ¹³C NMR (CDCl₃, 75 MHz): δ169.76,157.29, 145.35, 129.72, 122.66, 115.20, 114.91, 111.89, 67.34, 62.18,42.12, 36.16, 32.13, 31.61, 29.89, 22.91, 14.48. High resolution MSanalysis of the PDP-EA matched exactly with the calculated mass forC₂₅H₄₃NO₃, [M+H]⁺ of m/z 406.3321.

Plant Material and Cultures—

Ten mg Arabidopsis thaliana (ecotype Col-0) seeds were surfacesterilized and then stratified in the dark for 2 days at 4° C. prior tosowing in liquid (75 ml) or solid Murashige and Skoog (MS) medium (14).Growth of seedlings was in 16 h-light/8 h-dark cycle (60 μmol·m⁻²·s⁻¹)for 11 days at 20° C.

Plasmid Constructs—

The recombinant plasmid, rat FAAH1-pTrcHis2 (NCB Accession #NP_077046),was provided by Dr Benjamin Cravat's laboratory (34) and the plasmidAt-FAAH-pTrcHis2 (At5 g64440, UniProt #Q7XJJ7) was constructed asdescribed in prior studies. The expression constructs were introducedinto chemically competent E. coli TOP10 cells as host as described inthe manufacturer's instructions.

Protein Expression and Solubilization for Enzymatic Assays—

The different cell lines were grown in 250 ml of LB medium with 100μg·ml⁻¹ of filtered ampicillin to an A₆₀₀ of 0.6 and induced with 1 mMIPTG for 4 hours at 37° C. Each culture was centrifuged at 5000 rpm for10 minutes at 4° C. in a Beckman tabletop centrifuge (rotor, GH 3.7).The pelleted cells expressing rat FAAH1 or At-FAAH1 were resuspended in10 ml of lysis buffer A (50 mM Tris-HCl, pH 8.0, 100 mM NaCl, 1%TritonX-100) or 10 ml of lysis buffer B (50 mM Tris-HCl, pH 8.0, 100 mMNaCl, 0.2 mM DDM). After incubation on ice for 30 min, resuspended cellswere sonicated on ice with ten, 30-sec burst at 50% intensity with30-sec cooling (ice) period between bursts. Each crude lysate wascentrifuged at 13,000×g for 20 min at 4° C. in a Sorvall RC 5C modelultracentrifuge (Sorvall rotor, SS-34). The supernatant was applied to aQIQIEXPRESS® NI-NTA Fast Start (QIAGEN®) column and the proteins werepurified according to the manufacturer's instructions. The purifiedfractions (2 ml) were concentrated, and imidazole was removed withbuffer C (50 mM Bis-Tris propane-HCl, pH 9.0, 0.2 mM DDM) byfiltration-centrifugation using Centricon YM-30 (Millipore, Bedford,Mass.) devices. The protein concentration was estimated by Bradfordreagent (Sigma; St. Louis; Mo.) against a BSA standard curve, and thepurity of the proteins was evaluated by SDS-PAGE gel and westernblotting. The rat or At-FAAH proteins were aliquoted (20 μl) and storedat −80° C. up to several months and thawed once for use.

Plant Protein Extraction—

After 11 days in liquid culture the plant material was rinsed withmilliQ water and then blotted dry. With a mortar and pestle the plantmaterial (500 mg) was ground with liquid nitrogen and then with 2 ml ofplant protein solubilization solution (0.1 M potassium phosphate buffer,pH 7.2, 400 mM sucrose, 10 mM KCl, 1 mM EDTA, 1 mM EGTA, 1 mM MgCl₂)with 0.2 mM of DDM. The crude extract was vortexed (full power) for 1min then incubated at 4° C. for 30 min with regular shakes. The crudeextract was centrifuged at 2000 rpm at 4° C. for 10 min in a Beckman(rotor, GH 3.7). The supernatant, containing the total solubilizedproteins, was stored at 4° C. up to 2 days.

SDS-PAGE and Western Blotting—

Each aliquot (rat or At-FAAH protein) was separated by SDS-PAGE (10%resolving gels) according to Shrestha, R., Dixon, R., and Chapman, K.(2003) Molecular identification of a functional homologue of themammalian fatty acid amide hydrolase in Arabidopsis thaliana. Journal ofBiological Chemistry 278, 34990-34997. The proteins were visualized ingels by Coomassie-blue staining, or proteins were electrophoreticlytransferred to polyvinylidene fluoride (PVDF) membranes (0.2 μm,Bio-Rad, Hercules, Calif.) according to the protocol described elsewhere(10). The recombinant proteins expressing the HIS tag at the C-terminuswere detected by chemiluminescence using a 1-to-2000 dilution of mousemonoclonal anti-HIS antibodies (ABGENT San Diego, Calif.) and a solutionof 1-to-4000 dilution of goat anti-mouse IgG conjugated to a peroxidase(Bio-Rad).

FAAH Assays on Purified Proteins—

The NAE amidohydrolase assays were conducted as previously described byShrestha et al and others with few modifications. The reactions wereconducted for 30 min at 30° C., in 150 μl of buffer C containingdifferent concentrations of radiolabelled NAEs, the new NAE-likecompounds and different concentrations of purified protein (see legendsof figures for more details in the composition of each reactionmixture). Enzyme reactions were terminated by the addition of hotisopropanol (70° C.). The lipids were extracted and the distribution ofthe radioactivity was evaluated by radiometric scanning of TLC plates asdescribed in Shrestha, R., Kim, S., Dyer, J., Dixon, R., and Chapman, K.(2006) Plant fatty acid (ethanol) amide hydrolases. Biochimica EtBiophysica Acta-Molecular and Cell Biology of Lipids 1761, 324-334.

Plant Amidohydrolase Assays—

The reactions were conducted at 30° C. for 2 hours in buffer C with 300μM of PDP-EA or cardanol-EA and 200 μM of radiolabeled NAE 12:0.Reactions were initiated by adding 5 μg of total protein and terminatedby the addition of hot isopropanol. Lipids were extracted and analyzedas above.

Ethanolamine Inhibition Assays—

Assays containing 0.3 μg purified FAAH protein were first incubated with100 μM of PDP-EA or cardanol-EA and then with different concentrationsof ethanolamine (0-100 mM) (Vf=150 μl of buffer C). Reactions wereinitiated by adding 100 μM of radiolabeled NAE and terminated asdescribed. The lipids were extracted and the total distribution of theradioactivity was calculated as above.

Primary Neuronal Culture—

Commercially obtained Sprague/Dawley rat E18 cortical tissue was allowedto settle for 5-10 minutes at room temperature, the shipping media wasremoved (reserved at 37° C.), and the tissue was enzymatically treatedwith NeuroPapain dissolved in NeuroPrep Medium (2 mg/ml, 2.5 ml) for 28minutes at 37° C. with gentle swirling every 7 minutes. Treated tissuewas centrifuged for 1.5 minutes at 200×g and the cells were dissociatedby gentle trituration in 1 ml of the reserved shipping medium. Cellswere collected by centrifugation as above and re-suspended by gentletrituration in 1 ml of NeuroPure plating medium. Viable cells werecounted, (Nexcelom Auto T4; Nexcelom Bioscience LLC. Lawrence, Mass.)re-suspended in 9 ml of NeuroPure plating medium plus enough Neurobasalmedium (supplemented with B27; GlutaMAX I, 2 mM; Penicillin, 50 U/ml;Streptomycin, 50 μg/ml) to achieve a density of 250,000 cells/ml, andseeded in BD PureCoat™ black-walled amine-coated 96-well plates in a 100μl volume. Cultures were maintained at 37° C., 5% CO₂, 95% humidity for7 days prior to experiments with a 50% media exchange on day 3.

Effects of Cardanol-EA on Cultured Primary Neurons—

One hundred millimolar of cardanol-EA in DMSO was diluted 1:5 in warm40% 2-hydroxypropyl-β-cyclodextrin dissolved in DMSO and incubated for10 minutes at 50° C. prior to serial dilution in warm Neurobasal mediacontaining antioxidant-free B27 supplement, GlutaMAX I (2 mM),penicillin (50 U/ml), and streptomycin (50 μg/ml). Growth media wasexchanged for 100 μl antioxidant-free media containing serial dilutionsof cardanol-EA or vehicle (0.6% DMSO, 0.2%2-hydroxypropyl-β-cyclodextrin) and plates were incubated as above for1-2 hours. Oxidative stress was induced by the addition of concentratedtert-butyl hydrogen peroxide (tBHP) to achieve a final concentration of7.5 μM. Controls were treated with an equivalent volume of PBS. After16-18 hours, the cell culture medium was replaced with 100 μl pre-warmedPBS containing 5 μg/ml calcein-AM and plates were returned to theincubator for 30 minutes. Cell viability was determined by measuringcalcein fluorescence on a FlexStation3 plate reader (Molecular Devices,Sunnyvale, Calif.) at 485/525 nm excitation/emission with a 515 nmemission cutoff, subtracting the background, and normalizing to thevehicle control. Three separate experiments obtained from differentcultures (different animals) of primary neurons were performed. For eachcondition, six replicate wells were measured and the mean value was usedfor statistical analyses. Data was analyzed and plotted using Prism 5.0(GraphPad Software Inc., La Jolla, Calif.).

Treatment of Cultured Primary Neurons with FAAH Inhibitors or Substrate—

The FAAH substrate, NAE 16:0 (N-palmitoylethanolamine), was emulsifiedin 40% 2-hydroxypropyl-β-cyclodextrin dissolved in DMSO by sonication at50° C. to a final concentration of 50 mM. The FAAH inhibitors MAFP andURB597 were dissolved in DMSO at a concentration of 100 mM. Growth mediawas exchanged for 100 μl antioxidant-free media or antioxidant-freemedia containing vehicle or serial dilutions of substrate or inhibitorand plates were incubated as above. After an hour, 5 μl of 2×10⁻⁸cardanol-EA in anti-oxidant free media pre-diluted as above was added tothe conditions indicated, plates were gently mixed and returned to theincubator. After another hour, oxidative stress was induced as describedabove. Viability assay, replicates, and analyses were performed asdescribed above.

The use of the disclosed method is contemplated for use in conjunctionwith strategies to exacerbate cell death (e.g. combination therapy forexisting oncology therapies such as enhancement of radiation and/orchemotherapy, surgery, and the like. The method may also be used inconjunction with chemo-sensitizing agents that are targeted atlipid-signaling pathways effected by disease processes or as a modulatorof endocannabinoid signaling in applications ranging from cytoprotectionto cellular development and excitable cell function. The method may beused for therapeutic applications where manipulation of localizedendogenous NAE levels might be desired or in situ regulation of NAEmetabolism. The method may be used for modulation of appetite and/orfeeding behavior by decreasing the endogenous levels of acylethanolamideagonists in animal systems and/or clinical applications (e.g. weightloss therapy, agricultural applications to control drop damage by pests,etc.). The method may be used to decrease the level of NAEs inprokaryotic and/or eukaryotic cells, animals, humans, microorganisms byapplication of the compounds as pharmacological reagents that enhanceNAE degradation.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

What is claimed is:
 1. A method for enhancing amidohydrolase activity offatty acid amide hydrolase in an animal, the method comprisingadministering a composition of matter consisting essentially of aphenoxyacyl-ethanolamide to the animal such that hydrolysis ofN-acylethanolamines (NAEs) by fatty acid amide hydrolase (FAAH) in theanimal is enhanced relative to a substantially identical animal that hasnot been administered with the phenoxyacyl-ethanolamide, wherein thephenoxyacyl-ethanolamide is represented by a structure:

wherein R is an aliphatic side chain.
 2. The method of claim 1, whereinthe aliphatic side chain has between thirteen and fifteen carbons. 3.The method of claim 1, wherein the aliphatic side chain has fifteencarbons.
 4. The method of claim 1, wherein the aliphatic side chain isun-branched and has sixteen carbons.
 5. The method as recited in claim1, wherein the animal is a mammal.
 6. The method as recited in claim 1,wherein the animal experiences exacerbated cell death relative to thesubstantially identical animal.
 7. The method as recited in claim 1,wherein the animal experiences exacerbated cytostasis relative to thesubstantially identical animal.
 8. The method claim 1, wherein thealiphatic side chain is saturated.
 9. A method for enhancingamidohydrolase activity of fatty acid amide hydrolase in an animal, themethod comprising administering a phenoxyacyl-ethanolamide compositionto an animal such that hydrolysis of N-acylethanolamines (NAEs) by fattyacid amide hydrolase (FAAH) in the animal is enhanced relative to asubstantially identical animal that has not been administered with thephenoxyacyl-ethanolamide composition, wherein thephenoxyacyl-ethanolamide composition is represented by a structure:

wherein R is an aliphatic side chain; wherein the aliphatic side chainhas at least one double bond.
 10. The method of claim 9, wherein thealiphatic side chain has at least one double bond but no more than threedouble bonds.
 11. A method for enhancing amidohydrolase activity offatty acid amide hydrolase in an animal, the method comprisingadministering composition of matter consisting of aphenoxyacyl-ethanolamide to an animal such that hydrolysis ofN-acylethanolamines (NAEs) by fatty acid amide hydrolase (FAAH) in theanimal is enhanced relative to a substantially identical animal that hasnot been administered with the phenoxyacyl-ethanolamide, wherein thephenoxyacyl-ethanolamide is represented by a structure:

wherein R is an aliphatic side chain with between twelve and twentycarbons.
 12. The method of claim 11, wherein the aliphatic side chain isun-branched and has fifteen carbons.
 13. A method for enhancingamidohydrolase activity of fatty acid amide hydrolase in an animal, themethod comprising administering a phenoxyacyl-ethanolamide compositionto an animal such that hydrolysis of N-acylethanolamines (NAEs) by fattyacid amide hydrolase (FAAH) in the animal is enhanced relative to asubstantially identical animal that has not been administered with thephenoxyacyl-ethanolamide composition, wherein thephenoxyacyl-ethanolamide composition is represented by a structure:

wherein R is an aliphatic side chain with between twelve and twentycarbons, wherein the aliphatic side chain has at least one double bond.14. The method of claim 13, wherein the aliphatic side chain has atleast one double bond but no more than three double bonds.
 15. A methodfor enhancing amidohydrolase activity of fatty acid amide hydrolase inan animal, the method comprising administering a composition of matterconsisting essentially of a phenoxyacyl-ethanolamide to a mammal suchthat hydrolysis of N-acylethanolamines (NAEs) by fatty acid amidehydrolase (FAAH) in the mammal is enhanced relative to a substantiallyidentical mammal that has not been administered with thephenoxyacyl-ethanolamide, wherein the phenoxyacyl-ethanolamide isrepresented by a structure:

wherein R is a saturated aliphatic side chain with between twelve andtwenty carbons.